PROJECT SUMMARY Sleep during critical developmental windows is thought to be important for brain maturation. However, examination of a function for sleep in the earliest periods of nervous system development, when neurons are being born, has been limited by the lack of a tractable experimental system. The adult fruit fly is a widely studied model organism for sleep, but the major wave of neurogenesis in Drosophila begins during larval life and ends prior to adulthood. It has remained unknown whether larvae sleep. We present new approaches for long-term monitoring of larval behaviors, leading to identification of a sleep state in Drosophila larvae. We propose exploiting this system to understand how functional coupling of sleep and arousal brain centers changes throughout life. Using real-time behavioral monitoring in a closed-loop sleep deprivation system, we will examine how sleep loss in larvae affects cell division of neural progenitors, and determine the impact of early life sleep loss on adult learning and memory. We will then leverage the larval system to gain new mechanistic insights into how sleep loss is coupled to neurogenesis. Finally, we propose adaptation of our behavioral monitoring device to engineer a scalable system suitable for high-throughput closed-loop manipulation of behavior in larvae and other model organisms. Collectively, this work will generate novel tools and approaches for studying the role of sleep in the developing nervous system.